Method of and apparatus for producing refrigeration



Sept. 8, 1931. R, s. NELSON 1,322,109

METHOD OF AND APPARATUS FOR PRODUCING REFRIGERATION Q ,Filed ma 24, 1-930 ji J2 52 29 J7" 47 U 10 I 414 a 36 i i J3 1'; 16 65 J2 J5 45 J4 39 flz/awir fiadogp Life 460 a Patented Sept. 8, 1931 UNITED STATES PATENT I when,

RUDOLPH S. NELSON, OI ROCKFORD, ILLINOIS, ASSIGNOIQTO THE HOOVER COMPANY,

OF NORTH CANTON, OHIO,

A CORPORATION OF OHIO METHOD OF AND APPARATUS FOR PRODUCING REFRIGERATION Application filed May 24,

This invention relates to the art of refrigerating and more particularly to continuous absorption refr1gerating systems in which a plurality of refrigerants are simultaneously evaporated to produce a cooling effect.

Continuous absorption refrigerating systems employing a single refrigerant in combination with an inert or neutral gas are 1 well known. In' such a system the inert gas is circulated between the evaporator and the absorber and in accordance with Daltons laws of partial pressure maintains the total pressure in these" parts the same as that in the other parts of the system although the partial pressure of the refrigerant is lower 1n the evaporator and the absorber than 1n the'condenser and boiler. An example of such a system is found in the U. S. patent zoato Geppert 662,690 of Nov. 27, 1900. As an improvement on this systemit has previously been proposed to substitute a second refrigerating agent for the inert gas of the Geppert system so that both the main cooling agent-- and the auxiliary ressure equalizing agent may be condensed before they are introduced into the evaporator, the obiect being to increase the efficiency and the cooling effect of the system. Perhaps the best subso stances suggested for this purpose are ammonia and propane, these two refrigerants being condensible at about the same temperature and pressure and being practically miscible.

3 Now if two refrigerants are to be condensed at one temperature and evaporated, each in the presenceof the vapor phase of the other, at a lower temperature to produce a cooling effect, it is clear that they must be effectively separatedbefore they'can again be condensed at the higher temperature, there being no material difference in total pressure throughout the system. ,4 One 'way of separating them is effected by causing the gaseous mixture of the two refrigerants to come into contact with a solvent for one of them; In the case where ammonia and propane are used as the refrigerants, 60 water may be used as the solvent since it 1930. Serial No. 455,211.

' readily absorbs the ammonia but not the pro-- pane.

In attempting to o erate a refrigerating machine on this principle, difficulty has been experienced because of the fact that the auxiliary agent has condensed in parts of the apparatus Where it is desired and-intended that it be in a vapor or gaseous state. For

example, in attempting to operate apparatus heretofore proposed for carrying out the above principle in which an absorber and two condensers, one for the main refrigerant, and one for the auxiliary refri erant, were provided, it has been found t at the auxiliary agent condensed inthe absorber instead of the condenser provided for that. purpose.

In orderto make the machine operate, it is necessary to vaporize the liquefied auxiliary agent collected in the absorber. Where annnonia and propane are used as the re frigerants, the propane liquid floats on top of the solution in the absorber. By carefully controlling the circulation of the solution, just the right amount of heat may be carried y convection from the heaterfor the boiler to the absorber to drive ofi' this liquid propane. This requires the use of pipes of certain dimensions and the supply of heat to the boiler must be just right for these re.- quirements. If too much heat'is carried to the absorbers, the solution does not properly absorb the ammonia. If too little is carried thereto, the liquid propane is not vaporized.

In order to overcome these and other difliculties, an object of the present invention is to provide novel means for heating the absorber to the required temperature in the iary agent may be formed artificially before the apparatus is put into operation.

Further objects reside in the methods of producing refrigeration and of efiectively separating two refrigerants.

Other objects and advantages reside in certain novel arrangements and construction of parts as will be apparent from the following description taken in connection with the accompanying drawing in which The single figure is a diagram of an absorption refrigerating system embodying certain novel features and illustrating one form of apparatus adapted to carry out the principles of the invention.

Referring to the drawing, the system is there shown as consisting of a generator or boiler G, rectifier R, condensers C and C evaporator E, absorber or separating vessel A, heat exchanger H and the temperature regulating coil T, these vessels being connected by suitable conduits as shown. All of the parts may be made of steel. In general they are cylindrical in shape so that ordinary seamless steel tubing may be used in manufacturing them. For purposes of description, itwill be assumed that the apparatus is charged with ammonia, propane and water, although the invention is not limited to the use of these fluids.

The generator G comprises a hollow shell having end closures or heads 11 and 12 at the top and bottom thereof. The lower end 12 is provided with an inverted cup 13 which is welded or otherwise secured to an opening therein and which is adapted to receive an electric cartridge heating element 14. Obviously a gas flame or other heating means may be employed in place of the electric heater.

In normal operation a solution of ammonia circulates through the generator. For conducting the solution into the generator a pipe 15 extends through the lower end 12 of the generator proper and is connected to' a small coil of tubing 16 which is wrapped around theinverted cup 13. The upper end of the coil 16 is connected to a vertically extending pipe 17 which may be reversely bent at its upper end as shown. By this means when current passes through the electric heater 14, bubbles of ammonia gas are generated in the coil 16 and as they rise through the pipe 17 lift or pump the solution to the main body of the generator. A similar arrangement of a gas lift pump in a refrigerating system is shown and described in the U. S. patent to Altenkirch 1,728,742.

In addition to the ammonia gasgenerated in the gas lift pump, an amount is driven off by the application of heat tothe-main portion ofthe generator. The expelled gas passes upwardly through anopening in the closure 11 and into the rectifier R which is provided with suitable bafiles as shown for removing water vapor which is driven off with the ammonia. The upper end of the rectifier is connected to condenser C through the pipe 21. As ammonia is driven off from the solution in the generator the weak solution is conducted away through the conduit 23.

The condensers C and C referred to'above may be of any suitable construction. For the purposes of illustration they are shown as consisting of a small pipe coiled inside of a larger one through which cooling water is adapted to circulate. The inner pipes are indicated by the reference characters 24 and 25 on the drawing while the cooling jackets are indicated by the numerals 26 and 27.

For reasons which will be more apparent from the description which is to follow as to the operation of the system, it is important that the inner pipes 24 and 25 of these condensers be of small diameters preferably not over a quarter of an inch inside diameter. The condensers, and particularly the propane condenser, should be located a considerable distance above the evaporator so that fluid columns may form in the lower portions of the pipes 24 and 25. It is desirable that the propane condenser be located sufficiently high that the distance between the lower portion thereof and the top of the evaporator may be at least two and one half times the height of the liquid in the absorber A. It may be desirable to extend the cooling jackets 26 and 27 over the lower portions of the pipes 24 and 25 under some conditions. On the drawing the pipes connected to the condensers are v shown broken so as to save space in illustrat- The evaporator E is so constructed that liquids entering through the pipes 24 and 25 do not mix so long as they are in the r liquid phases but each liquid is exposed to the vapor phase of the other. For a full disclosure of this evaporator and the manner in which it operates reference may be had to my co-pending application, Serial No. 423,125, filed Jannary 24, 1930 for evaporators for refrigerating systems. As herein shown it consists of a cylindrical shell 29 having end closures or heads 30 and 31. The pipes 24 and 25 extend through the shell 29 near the upper end.

.effect. The vaporized fluids are conducted out of the evaporator through a conduit 35 connected to the lower end piece 31. Any

denser.

liquid which may have been supplied to the evaporator and not vaporized is also drained 1 away through the pipe 35.

The absorber or separating vessel A consists merely of a cylindrical drum made'up of a shell 36 and end pieces 37 and 38. It

may be cooled by circulating water through fluid between the pipes and 41 and another,

designated 43 for opening the pipe 25 to the atmosphere or to a charging cylinder when desired.

' provided by this construction.

For supplying absorption liquid to the absorber a conduit 44 is connected to the shell 36 as shown. 5

Adjacent the absorber a portion ,of this pipe together with a larger one 45 is formed into a coil, the pipe 45 providing a acket for a certain portion of the conduit 44. \Vater of a predetermined temperature may be circulated through the jacket 45 so that the absorption solution delivered to the absorber .may have a definite temperature. The lower end of the conduit 44 is connected to the outer jacket 46 of the heat exchanger H, the upper end of the jacket 46 beingconnected to conduit 23.

For use in starting, or if desired for continuously heating the upper part of the absorber during operation an electrical heating coil 47 surrounds-a portion of the absorber immediately above the inlet pipe 44. The amount of current flowing through this coil may be controlled by. any suitable means, (not shown) in order to maintain any desired temperature in this part of the absorber.

For conducting the absorption solution away from the absorber, the pipe 15 which is connected, to the coil 16 of the boiler and which forms the central pipe of the heat; ex-

changer H is connected to the lower head piece 38 of the absorber.

There are three cycles for fluid circulation One cycle which may be termed the ammonia cycle takes place from the generator G through the rectifier R, pipe 21, condenser (1,, evaporator E, absorber A, conduit 15, gas lift pump 16 and pipe 17 back to the generator. Another cycle which may be called the propane cycle takes place from the absorber A through the pipe 41, valve 42. pipe 25 of the condenser C valve 32, evaporator Eand pipe 35 back to the absorber. The third cycle which may be called the solution cycle takes place between the generator and the absorber, the circuit being from the generator through conduit 23, outer coil 46 of heat exchanger H, conduit 44, the absorber A and back to the generator through the conduit 15, coil 16 and pipe 17 The apparatus may be charged and operated as follows:

A quantity of ammonia solution is placed in the generator G and absorber A through suitable valves not shown, until thesame has filled these vessels up to approximately the levels shown by the dotted lines. The concentration of the ammonia solution used should be low and should be preferably even lower than 15% of ammonia by weight. Air may then be swept out of the apparatus in the usual manner, by forcing ammonia gas into the generator and absorber, the valves 32, 32, 42 and'43 being open at this time.

A quantity of liquid propane may then be.

placed in the absorber or in the condenser C The quantity of propane placed in the system should be sutficie'nt to insure the formation of a column of liquid in the pipe 25 and cover the plates 33 in the evaporator. As a factor of safety slighty more than this quantity may be added because of the fact.

that the condenser 0 evaporator and top portion-of the absorber-will be filled with propane vapor during the operation of the machine and a quantity of liquid propane remains in the absorber. The valves 32, 32', 42 and 43 provide means for artificially forming a column of propane in the pipe 25 asan initial step should this be necessary.

To form this column a cylinder filled with propane under pressure is connected-to the outlet pipe of the valve 32,,the valves 32 and 43 are closed and the valve 43 cracked slightly. Propane then flows into the pipe 25. The charging valves to the generator and absorber and the valves 32 and 43 may then be closed, the valves 32 and 42 opened and heat applied to the generator thus causing' delivery of ammonia gas to the condenser pane from the absorber A to the condenser C 1 it is necessary to maintain at least the upper' portion of the absorber at a temperature higher than that of the condenser C Under normal operating conditionsthis difference in temperature should be at least 20 degrees F. Since the efliciency of the absorption of ammonia is dependent upon the lower portion of the absorber being cool, cooling water should of course be circulated through the coil 40. If the machine is operated in a warm room the effect of air circulating around the top portion of the absorber should be taken into consideration, and if the area of the absorber is sufficiently large as compared With \the amount of solution therein, warm air alone may be sufficient to maintain the necessary temperature difference. Preferably the heat of the atmosphere should not be relied upon for this purpose, however and means has been provided for accurately controlling the temperature of the upper part of the absorber. Either the temperature regulating coil T or the electric heater 47 or both may be used for this purpose. The water entering the absorber through the pipe44 is normally warmer than that leaving through the pipe 15 so that the coil ,T need not effect a radical change in temperature conditionsin the pipe 44, but it is very useful in maintaining uniform and optimum temperature conditions 1n the absorber.

It has been found that a machine constructed like that illustrated operates to produce a cooling effect when the cooling water to the condensers and the coil 40 on the absorber is at a temperature of between and degrees F. while that supplied to the jacket 45 of the coil T is between 80 and 90 degrees F.

' Under these conditions the two refrigerants condense in their respective condensers, form columns in the pipes 24 and 25 and flow into the evaporator. As the refrigerants trickle downover the plates provided in the evaporator, vaporization of both takes place, the vapor of each refrigerant exerting its pressure independently of the other so that althou h the total pressure in the evaporator is only slightly greater than elsewhere in the system, the partial pressure of each refrigerent vapor is less. As vaporization takes place initially the pressure in the evaporator rises slightly.

This excess pressure becoming large enough to overcome the liquid column head in the absorber, bubbles of ammonia and propane are forced into the lower portion of the latter through the pipe 35. As these bubbles mix with the weak solution coming to the absorber through the pipe 44, both refrigerants are changed to a condensed fluid phase, that is, the ammonia is absorbed and the propane condensed. As the-propane rises, it'is heated as explained above and passes in gaseous form through the conduit 41 into the condenser C where' it is again condensed to complete its cycle.

The ammonia which is absorbed in the solution in the absorber is conducted through the pipe 15 into the generator through the gas lift pump 16 from which it isagain expelled in gaseous form into the condenser C to complete its cycle.

The solution thus deprived of ammonia returns to the absorber or separator through the pipe 23, jacket 46 of the heat exchanger and the pipe 14, as explained above.

Since it is impossible to absorb all the ammonia some will remain in a gaseous state and pass with the propane into thecondenser C Unless ammonia is removed from the condenser it will collect there until its partial pressure at this point'is about the same as that in the evaporator, under, which conditions it would of course be impossible to condense propane in the condenscrC and evaporate it in the evaporator at a lower temperature. Some means must therefore be provided to remove the ammoniafrom monia condenser C it will be removed therefrom in the same way. I

It will thus be seen that a refrigerating system has been provided in which two re frigerants are simultaneously evaporated and are then separated so that they may be co densecl in their respective condensers. ince the drawing is only diagrammatic in nature it is obvious that in constructing an apparatus in accordance with the principles of the invention, various expedients may be resorted to and various changes may be made in the arrangement and construction of the various parts Without departing from the spirit of the invention. The vessels may bemade of different shapes and dimensions so long as they do not interfere with the intended circulation and liquid levels. It is also within the scope .of the invention to regulate the flow of fluids in any of thevarious pipes by the provision in which the'ammonia may be absorbed by an absorption liquid, means for cooling the lower portion of the absorber, and means for heating the upper portion of the absorber to vapaorize liquid propane therein.

2. efrigerating apparatus adapted to produce cooling effect by the evaporation of ammonia andpropane includin an evaporator in which said ammonia an propane may simultaneously evaporate, an absorber in which the ammonia-may be absorbed by an absorption liquid, means for cooling the lower portion of the absorber, and means for heatingtheupper portion of the absorber to vaporize liquid propane therein, said heat ingmeans including an electrical resistance conductor surrounding the upper portion of said absorber.

4. Refrigerating apparatus adapted to produce cooling effect by the evaporation of a main refrigerant and an auxiliary refrigerant, said apparatus including an evaporator in which said refrigerants may evaporate, an absorber in which the main refrigerant is absorbedby an absorption liquid, a generator for expelling the main refrigerant from the absorption liquid, a condenser for said mam refrigerant connected between said generator and said evaporator, a condenser for said auxiliary. refrlgerant connected between said absorber and said evaporator and means for causing the auxiliary agent to pass through a cycle in which it is vaporized in the evaporator, liquefied in the lower, portion of the absorber, again vaporized, in the upper portion of the absorber,'again liquefied in the condenser andreturned to the evaporator.

5. Refrigerating apparatus adapted to I produce a cooling efiect'by the evaporation of tion of the absorber, again vaporized in the a main refrigerant and an auxiliary refrigerant, saidapparatus including an evaporator in which said refrigerants may evaporate, a n absorber in which the main refrigerant IS absorbed by an absorption liquid, a generator for expelling the main refrigerant from the absorption liquid, :a condenser for sa1d main refrigerant connected between said generat'of'r and said evaporator aa condenser-for said auxiliary refrigerant connected between said absorber and sa1d evaporator and means evaporator, said means including a device for coolingfluids in the lower portion of the absorber and a device for heating fluids in the'upper portion of the absorber.

employing two refrigerants, an absorber,

mean-s for conducting a gaseous mixture of,

the refrigerants into said absorber, means for conducting a solvent for one of sa1d refrigerants mto sa1d absorber and means for heatan absorption refrigerating system ing one portion and cooling another portion of said absorber.

7. In an absorption refrigerating system employing two refrigerants, an absorber, f

means for conducting a gaseous mixture of the'refrigerants mto sa1d absorber, means for conducting a solvent for one of sa1d refrigerants into said absorber and means for malntaining the upper portion of said absorber at a higher temperature than the lower portion thereof.

8. In refrigerating ap aratus adapted to employ a plurality of re rigerants, the combination of an evaporator, a plurality of condensers situated above said evaporator, an absorber, conduits forconveylng one of saidrefrigerants 1n a'cycle through said absorber, one 'of said condensers and said evaporator back to sa1d absorber, a valve" located in the condhit from said absorber to saidcondenser, a second valve located in the conduit from said condenser to said evaporator and a valve connected to each of said conduits and adapted to open the same to the atmosphere or to a charging device whereby.

a column of liquid refrigerant may be rtificially formed in said condenser and the conduit from said condenser to the evaporator before the machine is placed in operation.

9. In absorption refrigerating apparatus adapted toemploy a main refrigerant and I an auxiliary pressure equalizing agent, the

combination with an absorber, a condenser,

an evaporator and conduits connecting the same, of means for circulatlng sa1d aux1l1ary agent between said absorber, condenser and evaporator, said means including a device for cooling the lower' portion of theab'sorber, a

device. for heatingthe upper portion of the absorber and a device for cooling said condenser whereby said auxiliary agent will be caused to condense in said absorber and evaporate therefromand again condense in said condenser. 1 v v 10. In refrigerating apparatus employing a main refrigerant and an auxiliary pressure equalizing agentgand having an evaporator and an absorber the method of circulating for;...causing the auxiliary agent to paiss the auxiliary pressure equalizing agent bethrough. a cycle in whichjit is vaporized in the evaporator, liquefied in the lower porupper portion of the absorber, again liquefied in the condenser and'returned to the applying heat to a portion of the absorber to vaporize the auxiliary agent and condensing the auxiliary agent at a level above the eva orator whereby it may flow back into t e evaporator by gravity. 11. In an absor tion refrigeratin system employing two ref iigerants, the com ination of an evaporator wherein both of said refrigerants may evaporate, a separating vessel, a conduit for conveying the vaporized refrigerants from said evaporator to said separating vessel, a generator means for circulating an absorption solution between said generator and said'separating vessel to convey one of said refrigerants to said generator, means for cooling a portion of sai se arating vessel to cause the other of said re rigerants to condense therein and form a layer on top of the absorption solution therein, means for heating said generator and a portion of said separating vesselto vaporize the refrig erants and means for condensing said refrigerants and returning them to said evaporator.

12. Ina refrigerating system of the absorption type employing two refrigerants, means for causing one ofsaid refrigerants to pass through a cycle in which it is separated from an absorption solution by the application of heat, condensed, evaporated to produce a cooling effect and returned to the absorption solution and means for causing the other of said refrigerants to pass through a cycle in which it is vaporized from a liquid base by the application of heat, condense and may condense in said vessel and separatefrom the solution by gravity and means for returning the refrigerants so separated into the evaporator in liquid form.

Si ed at North Canton, in the county of Star and State of Ohio, this 20th day of May, 1930. I

- RUDOLPH S. NELSON.

evaporated with the first mentioned refrigv erant for the production of cooling effect and again changed to a liquid phase.

18. In a refrigerating system employing a plurality of refrigerants, a vessel for separating said refrigerants after they have become mixed and means for heating a portion of said vessel to vaporize one of said refrigerants.

14. In an absorption refrigerating system employing a plurality of refrigerants, a vessel for separating said refrigerants and means for heating a portion of said vessel to vaporize one of said refrigerants, said means including a conduit adapted to convey an ab-, sorption solution to a portion of said vessel.

15. The method of reducing refrigeration including the steps 0 feeding a plurality of refrigerants in liquid phase into an evaporator, conducting the vaporized refrigerants from the evaporator into a separating vessel, changing the refrigerants to more dense fluid phase in said vessel and separating the same y gravit 16. The method of producing refrigeration including the steps of feeding two different refrigerants in liquid phases into an evaporator, conducting the-vaporized refrigerants from the evaporator into a separating vessel, changing the refrigerants to mcre jdense flu d phase in said vessel,-separating the after i same by gravity, vaporizin each refrigerant t as been separate from the other, 

